1. Field of the Invention
The present invention relates to a network system, a network connecting device, and a network connecting method, and, more particularly to a network system, a network connecting device, and a network connecting method for performing network connection.
2. Description of the Related Art
In recent years, according to the spread of personal computers (PCs) and the development of the Internet, many people access, using PCs in homes and work places, server devices provided on the Internet and download and use various content data or transmit and receive electronic mails. As the content data, it is also becoming more general to download audio data and video data through the Internet. For example, a technique for simultaneously providing, in a chat system for performing a chat through the Internet, plural people who participate in the chat with audio data in the same manner as text data and allowing the people to listen to the audio data is proposed (see, for example, JP-A-2005-242667).
As a new guideline for such a network, the DLNA (Digital Living Network Alliance) is known. In the DLNA guideline, a DMS (Digital Media Server) that records, accumulates, and provides contents and a DMP (Digital Media Player) that reproduces the contents are defined. A user can use both the DMS and the DMP simply by connecting the same to the network. The DMP finds out the DMS present in the network and automatically acquires a list of usable contents.
The user simply selects content that the user desires to view and listen to out of the prepared list of contents to automatically receive the content from the DMS. As the DMS, a PC, a home server, a DVD (Digital Versatile Disc)/HDD (Hard Disk Drive) recorder, and the like are assumed. As the DMP, a television, an AV (Audio Visual) component, a notebook PC, a PDA (Personal Digital Assistant), and the like are assumed. One device can have both the functions of the DMS and the DMP.
In the DLNA, Ethernet (registered trademark) or an IEEE (Institute of Electrical and Electronic Engineers) 802.11 wireless LAN is used as a transmission standard. TCP/IP (Transmission Control Protocol/Internet Protocol) is used as a communication protocol. DHCP (Dynamic Host Configuration Protocol) is used for dynamic allocation of addresses. HTTP (HyperText Transfer Protocol) is used for transmission and reception of contents. XML (eXtensible Markup Language) is used for description of messages transmitted and received between the DMS and the DMP. UPnP (Universal Plug & Play) is used for search for a usable server and acquisition of a content list.
In general, in the wireless LAN, since interception of communication content is easy, it is attempted to give safety same as that of wired communication to the wireless LAN by encrypting a packet to be transmitted and preventing an interceptor from knowing the content. Therefore, a WEP (Wired Equivalent Privacy) key or the like adopted as a security system of IEEE (Institute of Electrical and Electronic Engineers) 802.11b/g is used as encryption means. However, in the past, it is necessary to manually enter the WEP key. Since the WEP key has a large number of digits, a user has difficulty in correctly entering the WEP key. Further, since the user needs to keep the WEP key, it is also a lot of trouble to manage the WEP key.
There is also known a pairing system in which SETUP buttons are provided on a DMS side and a DMP side, respectively, a WEP key is exchanged between one device and the other device whose SETUP button is depressed in a predetermined time after the SETUP button of one device is depressed, and network connection is automatically established. However, when a third party depresses the SETUP button of a device with which users do not desire pairing, network connection is also established between the device and the other devices. Therefore, it is difficult to prevent intrusion of a malicious third party.